Change of Address: U.S. ZIP Codes: Addresses 101

U.S. ZIP Codes: Addresses 101

Addresses are actually more complicated than most people ever take the time to realize or appreciate. The concept of keeping track of where everyone lives in order to be able to send items via a courier to each other sounds simple but when you evolve from a small community to millions of people, the complications quickly get compounded. One of the basic elements of a U.S. Address is commonly known as a ZIP code (aka zone improvement plan, zipcode, zip, etc.). The ZIP code is used mostly for sorting purposes so that the mail going to someone can at least get to the nearest post office branch for distribution by a carrier.

ZIP Codes are numbered with the very first digit representing a group of U.S. States, the second and third numbers together represent a region in that group (a city or town for instance), and the final 2-digits more narrowly define the location (area or part of the city/town). ZIP Codes are often divided and/or changed in fact some minor monthly changes are actually very normal.

If you look at ZIP codes from a geographic perspective you will notice that the lowest numbers are in the Northeastern U.S. and then they first increase as you go South down the east cost and then go up as you move Westward (so Boston, MA is 02107, Atlanta, GA is 30303, Des Moines, IA is 50309, and San Francisco, CA is 94111). These are all just example ZIP codes but they help you understand the flow of ZIP codes quite a bit.

As was mentioned above, the first digit of a ZIP code represents a group of States. Here is a quick table which defines the actual state groupings:

First Digit of ZIP Code	Group of States
0	Connecticut (CT), Massachusetts (MA), Maine (ME), New Hampshire (NH), New Jersey (NJ), Puerto Rico (PR), Rhode Island (RI), Vermont (VT), Virgin Islands (VI)
1	Delaware (DE), New York (NY), Pennsylvania (PA)
2	District of Columbia (DC), Maryland (MD), North Carolina (NC), South Carolina (SC), Virginia (VA), West Virginia (WV)
3	Alabama (AL), Florida (FL), Georgia (GA), Mississippi (MS), Tennessee (TN)
4	Indiana (IN), Kentucky (KY), Michigan (MI), Ohio (OH)
5	Iowa (IA), Minnesota (MN), Montana (MT), North Dakota (ND), South Dakota (SD), Wisconsin (WI)
6	Illinois (IL), Kansas (KS), Missouri (MO), Nebraska (NE)
7	Arkansas (AR), Louisiana (LA), Oklahoma (OK), Texas (TX)
8	Arizona (AZ), Colorado (CO), Idaho (ID), New Mexico (NM), Nevada (NV), Utah (UT), Wyoming (WY)
9	Alaska (AK), American Samoa (AS), California (CA), Guam (GU), Hawaii (HI), Oregon (OR), Washington (WA)

There are other “special” ZIP codes for some of the U.S. territories as well as for some of the places in the country that get a lot of mail. For example, the Federal Citizen Information Center (FCIC) gets a lot of mail and accordingly has it’s own 5-digit ZIP. It is also true that the President of the United States also has his own personal ZIP code which is secret (the secret ZIP code is reserved for the First family to use as they see fit).

So the basic anatomy of a 5-digit ZIP code is pretty easy to follow and fortunately for everyone the digits do have a meaning. These aren’t just random numbers thrown together by a massive number-generating software program.

So the next time a clerk at a cash register asks you for your ZIP code you can now have a little better appreciation for the value they are most likely receiving from you. In general, not too much. But now you at least know a little bit more about 5-digit ZIP codes. If nothing else maybe you will think of this article… So that’s all for 5-digit U.S. ZIP Codes and their contribution to the basic anatomy of U.S. addresses.